Download Liver Fluke in Cattle

XLVets Fact Sheet
Parasitic Diseases
PD
Liver Fluke in
Cattle
Fluke infection has been recognised for generations, but over the past few years there has been
an alarming increase in the incidence of liver fluke. This has coincided with a greater geographic
distribution beyond the traditional at-risk, high rainfall areas. Increased pressure on maximising
herd productivity has meant that liver fluke and its impact has become an emerging area of
interest.
SIGNS OF LIVER
FLUKE INFECTION
The main clinical signs of fluke
infection are reduced growth rates, a
gradual depression of milk yield, and
stock that are generally not thriving.
Sheep are particularly susceptible
to fluke. Infection can cause
serious illness and even death.
However, fluke is often overlooked in cattle because the
signs are very subtle and clinical
disease is rare. An absence of
fluke symptoms and a lack of farm
history is no reason to leave fluke
risks unmonitored. A fluke control
strategy is still recommended.
Consequences
• A low grade infection of just 100
• Fluke infection (fasciolosis) can
reduce feed conversion and
depress appetite (dry matter
intakes can be reduced by as
much as 11%). This nutritional
stress depresses fertility and
compromises the cow’s immune
status.
• Fluke infection can also precipitate
other infectious disease such as
the Clostridial infection ‘Black
disease’ or it can compound
outbreaks of Salmonella.
• In essence fluke infection can
reduce lifetime performance.
Many farmers see the need to treat
for fluke infection in sheep where
symptoms can be more graphic,
yet fail to recognise the potential
production losses in cattle.
fluke has been shown to reduce
milk yield by 400 litres/cow/
lactation.
• Fluke has a detrimental effect on
milk fat content. Research has
shown untreated animals can
produce 10% less milk solids.
• Heavily pregnant dry cows in poor
body condition can experience
a fluke-associated nutritional
challenge in late pregnancy.
• Calf birth weights for fluke-infected
cows can be up to 10% lower.
• Young stock will experience poorer
growth rates giving reduced
efficiency for the rearing of
replacement heifers.
XLVets Committed to NZ farming
Liverfluke eggs
under a
microscope.
XLVets Liver Fluke in Cattle
Liver fluke
life cycle
Liver Fluke (Fasciola hepatica) is a
flat, leaf-like (3.5cm) parasite found
in the liver of grazing animals. Eggs
from adult female fluke pass in the
dung to contaminate pasture. When
conditions are suitable - damp and
warm (above 10o C) - the eggs hatch
to form mobile larvae that seek out
mud snails to complete their life cycle.
The presence of the amphibious mud
snails determines the distribution of
Parasitic Diseases
fluke. So the highest risk grazing are
wet areas and around pools of water.
The larvae multiply in the snails and
emerge to attach to the grass as
cysts.
The grazing animal ingests the cyst
when it breaks out as an immature
fluke to make its way to the liver.
The fluke tunnel through the liver and
if conditions favour, a massive hatch
and infection can cause severe and
permanent damage. The adult fluke
live in the bile ducts of the liver where
they feed on blood. This can amount
to half a millilitre per adult fluke per
day explaining the anaemia exhibited
by infected animals.
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DIAGNOSIS
Fluke diagnosis is not straight
forward and needs careful
interpretation, so speak to your
vet.
Fluke egg counts from faecal
samples indicate infection but
egg production is sporadic.
Blood sampling a random group
(young homebred stock would
be a good indicator) can reveal
the evidence of fluke infection.
Post mortem/meatworks
feedback provides a direct report
of fluke level in condemned
livers. Many abattoirs are doing
this now.
Bulk Milk ELISA testing is
available and can be used to
monitor the herd through the
season. Your vet can organise
this for you.
TREATMENT
Treatment is very effective but
needs to be targeted to the fluke
season and to recognise the variable
efficacy of product for the different
stages of fluke (early immature,
immature and adult). The milk
withhold of various products must
be also be considered and often
means treatment is targeted in the
dry period. Fluke treatments come
as drenches and injections and are
also available in combination with
worm treatments. The recognition
of fluke and a strategic approach to
treatment should be a component
of herd health plan reviews. A little
investment in health will go a long
way to alleviating the production
losses that can be associated with
liver fluke infection.
For more information contact your local XLVets practice:
www.lhvc.co.nz
[email protected]
XLVets Committed to NZ Farming. Go to www.xlvets.co.nz